1. Field of the Invention
The present invention relates to an asynchronous mobile communication system. More particularly, the present invention relates to a network connection method for a mobile terminal in an asynchronous mobile communication system that is capable of reducing connection latency and power consumption.
2. Description of the Related Art
Typically, in asynchronous mobile communication systems such as Global System for Communication (GSM), General Packet Radio Service (GPRS), and Universal Mobile Telecommunications System (UMTS), a mobile terminal acquires synchronization with a network during a network connection procedure. This is, when a mobile terminal is turned on, it scans frequencies and measures received signal strengths on the frequencies. If a best frequency is detected in accordance with the received signal strengths, the mobile terminal attempts to acquire synchronization with the network operating in the frequency band. After acquiring synchronization, the mobile terminal is served by the network.
In a conventional automatic network connection method, the mobile terminal performs frequency scan (power scan in GSM) and measures signal strengths of the frequencies. If a frequency having signal strength greater than a preset value is detected, the mobile terminal performs synchronization with the network on the frequency.
A conventional manual network connection method generates a list of frequencies as the result of the frequency scanning and signal strengths in order for a user to select one of the frequencies. If a frequency is selected from the list, the mobile terminal performs the frequency scan again. At this time, the mobile terminal scans the frequencies having the same operator ID as the selected frequency and selects one of the scanned frequencies. If a frequency is selected, the mobile terminal performs synchronization with the network.
In the conventional manual network connection method, the mobile terminal performs the frequency scanning twice when the user selects an operator. Specifically, the frequency scanning is performed on all frequency bands and is then performed on the frequencies in one of the frequency bands. However, such repeated frequency scanning increases network connection latency and power consumption of the mobile terminal.
Therefore, a need exists for an improved network connection method for a mobile terminal in an asynchronous mobile communication system capable of reducing connection latency and power consumption.